Usually, modules constituting a system are coupled to each other by one or a plurality of paths. When modules are coupled to each other by a single path and a failure occurs in any of the modules or on the coupling path, an influence range of the failure is restricted by blocking the relevant module and the coupling path to increase failure tolerance of the entire system (for example, refer to PTL 1).
Coupling modules to each other by a plurality of paths is intended to improve redundancy and performance. In this case, when a failure occurs in any of the modules, the module and all coupling paths are blocked. When a failure occurs on any one of the plurality of coupling paths, there may be cases where only the failed coupling path is blocked and operation is continued using the remaining paths.